Show the average 14-month-old baby a sealed jar of cookies, and you get some pretty predictable behavior. The child will reach for the treats and, when thwarted, look beseechingly at the nearest adult. The request for help  delivered with eye contact, gestures and often with pleading sounds  is unmistakable. But some babies don't do it. One little boy, captured on video by psychologist Wendy Stone at Vanderbilt University, repeatedly places a researcher's hand on the cookie jar but never once looks at her face to see why she isn't responding. Eventually, tragically, he gives up.

Show the average 18-month-old a video of toddlers at play, and you can bet that the tot will be mesmerized by scenes with strong emotion: a fight or kiss. But some babies have other interests. At the Yale Child Study Center, psychologists Warren Jones, Ami Klin and Sarah Shultz measure when toddlers stop blinking  a reliable indicator of rapt attention. The typical child will stare at the scene of a kiss, but a child with autism will be transfixed by the opening and closing of a door. (See six tips for traveling with an autistic child.)

Experiments like these, presented at a recent conference at Columbia University's Teachers College, are helping researchers identify the signs of autism at ever earlier ages. For parents, says Stone, director of Vanderbilt's Treatment and Research Institute for Autism Spectrum Disorders, "the average age of first concern is 17 months, though a diagnosis isn't typically made until age 3. That's a long time to be concerned and not know what to do."

In 2007, the American Academy of Pediatrics recommended that doctors begin screening babies for autism at 18 months, but researchers have yet to refine the tools for making a reliable diagnosis at that age. One issue, says Catherine Lord, director of the University of Michigan Autism & Communication Disorders Center, is that there is so much individual variability in how babies develop. Another challenge is that many of the signature signs of autism  delayed speech, repetitive movements or fixations on particular toys or objects  involve language and motor skills that babies have not yet acquired. That's why identifying the signs of autism before age 2 often involves the absence of typical behavior as opposed to the presence of aberrations.

Among the telltale signs of trouble at 12 months: not responding to one's name; not sharing interests through pointing and eye gaze; lack of joyful expression; an absence of babbling; difficulty establishing eye contact; and staring too long at inanimate objects (see FirstSigns.org for more early-warning signs). Investigators have identified these red-flag signs of autism by looking at early home videos of children who were diagnosed at age 3 or later and by studying the younger siblings of children with autism, who have relatively high rates  perhaps 15%  of the disorder. But no single behavior is indicative, and researchers believe that rather than being given a definitive diagnosis, tots with several of these behaviors should be identified as "at risk" and referred to early-intervention programs. (See pictures of a school for autistic children.)

Research strongly suggests that early intervention is key to improving outcomes for at-risk children. And by identifying these children at younger ages, scientists can better determine which aspects of autism are hardwired and which are the secondary results of living with the disability. There is also growing support in the autism-research community for the view that a significant number of children who are at risk could be protected from becoming fully autistic if they are assisted early enough and given the optimal intervention.

"The environment in the early years has an active role in shaping the brain," says Geraldine Dawson, a leading autism researcher and the chief scientific officer of the advocacy group Autism Speaks. "What we see in autism may be partly the result of not engaging with the social environment. So if you engage the baby through an intervention, you might prevent or at least reduce the development of autism symptoms." (See more about autism.)

Thus, the child who is not taking part in the typical parent-child dance  exchanging smiles and glances, pointing at something of interest, seeking attention  is missing out on a lot of learning and failing to lay the foundations for more complex social behavior. Rather than become experts on social cues, as most humans are wired to do, these children, observes Klin, tend to focus on the physical world  the opening and closing of doors and the properties of inanimate objects.

Several studies from across the country are looking at how to draw at-risk infants into the social world so that they will develop more normally. One National Institutes of Healthfunded study, at the University of Washington, begins intervention for at-risk babies at 8 months, says Dawson, who adds, "What we are doing is teaching the parents how to structure interactions to promote eye contact and babbling." Parents learn, for example, to engage their babies in settings where there are few distractions so that facial expressions and language are more salient. They also learn strategies to calm infants who tend to become agitated and stressed by social activity. The intervention is playful in spirit, says Dawson, adding, "Parents get very confident and are able to learn this quickly." The hope, she says, is that for some significant portion of children at risk, "we can begin before the full autism syndrome is present and prevent it from emerging."